Parking Brake System: Description and Operation
PARKING BRAKEDESCRIPTION
The parking brakes consist of the following components:
- Hand-operated park brake lever - automatic-adjusting
- Parking brake cables (2)
- Actuation levers and struts
- Duo-servo parking brake assembly (rear disc only)
All vehicles are equipped with a center-mounted, hand-operated parking brake lever mounted between the front seats (Fig. 134). This lever is an automatic adjusting type that continuously applies minimal tension to the parking brake cables to keep them in adjustment at all times.
The parking brake lever has a short output cable with an equalizer bracket attached to it that connects to the parking brake cables (Fig. 134). The output cable can only be serviced as part of the parking brake lever.
There is an individual parking brake cable for each rear wheel that joins a parking brake cable equalizer, attached to the parking brake lever, to the rear parking brakes. The parking brake cables are made of flexible steel cable. Both drum rear brakes and disc rear brakes use the same parking brake cable configuration, but the cables are different.
On vehicles equipped with rear drum brakes, the rear wheel service brakes also act as the vehicle's parking brakes. The rear drum brake shoes, when acting as parking brakes, are mechanically operated using an internal actuating lever and strut connected to the flexible steel parking brake cable.
The parking brakes on vehicles equipped with rear disc brakes consist of a small duo-servo brake assembly mounted to the disc brake caliper adapter (Fig. 135). The hat (center) section of the rear brake rotor serves as the braking surface (drum) for the parking brakes (Fig. 136). This parking brake application uses the same operating cable configuration as the drum brake equipped vehicles, but different cables.
OPERATION
When the parking brake is applied, the equalizer bracket on the lever output cable pulls on both parking brake cables, thus applying the brake shoes (rear drum brakes) or parking brake shoes (rear disc brakes).
The brake shoes are mechanically operated by an internal lever and strut connected to the parking brake cables.
The parking brake lever automatic-adjusting feature continuously applies minimal tension to the parking brake cables to keep them in adjustment at all times. Therefore, the parking brake cable system does not require adjustment. Proper parking brake system adjustment is obtained by proper drum brake or drum-in-hat brake shoe adjustment. When service is needed, the lever auto-adjust mechanism must be reloaded and locked out before service can be performed.